Society for Popular Astronomy

Anyone know how difficult (relative to recent missions) it would be to calculate a trajectory and send a probe into an orbit around a theoretical planet that is orbiting our nearest neighbour? Considering it would take about 50,000 years at today's speeds to get there it is an exercise of the mind only but I thought it would be interesting to enquire whether such a thing is possible. I also assume that a probe sent to a planet that would take nearly nine years to make any kind of communication is just one step away from being litter.

Regards,

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200mm Newtonian, OMC140, ETX90, 15x70 Binoculars.

I'm no expert, but my feeling is that this is the sort of thing that is possible within far less than 50,000 years by using nanoprobes. It has to be easier to accelerate a probe the size of a pen, say, to a sensible fraction of the speed of light than something the size of the Huygens or even the Beagle probes.

Mind you, it's one thing to get it there, quite another to make meaningful observations and transmit them back, or even to slow it down again so that it spends more than a few minutes there!

Robin

Hi Robin,

Yes that's kind of what I mean. We will get faster and smaller but if you travel at a good fraction of the speed of light it will take you forever to slow down. Is this the sort of thing that can be done when an instruction takes years to get there? There will be no planets to gravity assist, etc. and not much fuel, so does every detail have to be programmed into the probe at the start? Is it possible to undertake such a thing without making flight adjustments?

This is why perhaps after a certain distance there is no point in thinking about "unmanned" probes. You would need to make adjustments locally. But of course a manned probe doesn't necessarily mean a person, it could mean a very smart computer that can adapt to the environment. This would be a probe that was independent of Earth and wouldn't be able to reliably report back. I suppose it would simply be a calling card inthe unlikely event that something might be out there and gave a monkey's about a piece of tin that either fell to ground or was discovered orbiting.

Anyway my initial thought was do we know the maths and nearly have the technology in theory to send something into orbit around an extra solar planet now? Even if it takes thousands of years to get there.

Regards,

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200mm Newtonian, OMC140, ETX90, 15x70 Binoculars.

Shouldn't that be d**n ?

You're right stella but I have annoyingly changed it to something else and people will have to think hard about what you mean now. Oh and by the way, is it monkeys or monkey's and if the latter, monkey's what? Any idea?

Regards,

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200mm Newtonian, OMC140, ETX90, 15x70 Binoculars.

Well, if it's "monkeys", that indicates plurality as in "As mischevious as a troupe of monkeys".

But if it's "monkey's", that indicates possession, as in "I'll be a monkey's descendant"

But aren't we getting a little Off-Topic?

Ok. Anyway I've thought about it and can answer my own question in the negative.

Best wishes,

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200mm Newtonian, OMC140, ETX90, 15x70 Binoculars.

Getting back to the point about probes, and answering Joe's initial question, my feeling is that the control of the probe when it reaches Proxima is comparatively easy -- you program it to react to what it finds. Navigating it there is also easy -- you send it in the right direction and eventually it will encounter a bright object which will be Proxima. Quite possibly you would program it to aim for such a point close to the star so as to use a slingshot to then take it to Alpha a few months later.

Some recent planetary spacecraft have tested out methods of allowing the craft to make its own navigational decisions (can't recall which ones offhand). One difficulty with a nanoprobe I think would be giving it a transmitter sufficiently powerful that it could get a signal back to Earth. Probably it would have to conserve power (and store solar radiation from Proxima) and simply emit a single timed info-laden beamed beep every so often. Measuring the timing and frequency of these beeps would tell us where it was, just as Earth-based radiotelescopes picked up the carrier wave from the Huygens probe, whose transmitter was no more powerful I believe than that on a mobile phone, making it possible to work out its path through the atmosphere of Titan.

The real difficulty would be accelerating the nanoprobe in the first place, and giving it some onboard means of course correction, without making it too large.

Not that I know what I'm talking about, of course!

Robin

No Robin, you do have an idea of what you're talking about and what you say makes good sense and invites lots of comment. Without going through all of your points just yet, I wonder if you know how accurate we can know the orbit of a planet in 10,000 years? Oh and an exoplanet for that matter. If we wanted to land Huygens on Titan in 10,000 years time would we be able to calculate where it would be? Or are the effects of gravity from all the other bodies in the solar system too complicated to allow a precise calculation. I don't really know. I know that Skymap can tell you where something will be in 100 years time but is it accurate and can it predict positions in 10000 years? It seems to me that it is complicated but relatively easy to land a probe on a body in the solar system, we are seeing it every few years, but I wonder if the complications of distance, extreme distance, and perhaps more importantly time, means that we would be dealing with something different altogether.

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200mm Newtonian, OMC140, ETX90, 15x70 Binoculars.

Dear Joe, Robin, not least Stella and anyone else out there!
Unlike the rest of you I can speak with authority on this matter. But to tell the truth not much!
I did try to get in the Fleet Air Arm to be a pilot when I was a lad but they would not have me. I ended up a squaddy in the army for two years but that was 50 years ago now so I do not think the SPA will select mw to go on your space jaunt to your planet. However, as Robin already said I suspect the maths is not too difficult ( I would get my astronomy assistant (maths 2nd class to do the calculations for me of course so I would find it easy). However, I am inclined to think one of the hard bits would be making sure there is a planet orbitting the star before you set out. Being a coward if I were going I would not slow down approaching the Star\planet until I was absolutely sure the planet existed and was what it is supposed to be. If not at least keeping the speed up would help me get back home. Incidentally if I had travelled fast enough would there be any chance of me growing younger on the space journey and getting in the Fleet Air Arm as a pilot. Perhaps not,but I would not want to join the Army again.
Best wishes from the grumpy old codger Cliff